Fluid–Structure Interaction Simulations of a Wind Gust Impacting on the Blades of a Large Horizontal Axis Wind Turbine

Gilberto Santo,Wim Van Paepegem,Joris Degroote,Mathijs Peeters

doi:10.3390/en13030509

Abstract

The effect of a wind gust impacting on the blades of a large horizontal-axis wind turbine is analyzed by means of high-fidelity fluid–structure interaction (FSI) simulations. The employed FSI model consisted of a computational fluid dynamics (CFD) model reproducing the velocity stratification of the atmospheric boundary layer (ABL) and a computational structural mechanics (CSM) model loyally reproducing the composite materials of each blade. Two different gust shapes were simulated, and for each of them, two different amplitudes were analyzed. The gusts were chosen to impact the blade when it pointed upwards and was attacked by the highest wind velocity due to the presence of the ABL. The loads and the performance of the impacted blade were studied in detail, analyzing the effect of the different gust shapes and intensities. Also, the deflections of the blade were evaluated and followed during the blade’s rotation. The flow patterns over the blade were monitored in order to assess the occurrence and impact of flow separation over the monitored quantities.

Highlights

Renewable energy sources have been gaining more importance in the last few decades as part of the strategies adopted by countries all over the world to limit the use of fossil fuel and fight pollution and global warming
The adoption of more slender blades has led to higher deflections during normal operation, and more interest toward the fluid–structure interaction (FSI) phenomenon in modern wind turbines
A detailed and high-fidelity aeroelastic model was employed, implicitly coupling a computational fluid dynamics (CFD) solver based on an overset technique and a computational structural mechanics (CSM) solver, loyally reproducing the characteristics of the composite material of each blade

Summary

Introduction

Renewable energy sources have been gaining more importance in the last few decades as part of the strategies adopted by countries all over the world to limit the use of fossil fuel and fight pollution and global warming. Recent works have computed that, while operating in design conditions, the flapwise deflection of a modern horizontal-axis wind turbine (HAWT) blade is in the order of 6–7% of its span [2,3,4] Their deflections have a sensible impact on the produced power, affecting its oscillation or introducing a reduction up to 6% [2,3,4,5,6]. Despite its low computational cost, BEM theory is affected by many limitations, including the need to include tip-loss corrections to account for a blade of finite length [10] Another class of widely used models are the actuator models, where the blades are represented by lines or surfaces exchanging momentum with the incoming wind flow [11,12,13].

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Results

Conclusion